With the expanding commercial interest in the generation of small nano-scale electronic devices there is a need for the generation of a new class of conductive molecules that are functionalized to be adaptable for nano-device fabrication. However, the discovery of new and improved conductive molecules for use in nano-electronic devices is hampered by a number of problems. Little is known about the specifics of how conductive molecules work. Additionally, it is difficult to connect conductive molecules to electrodes and even more difficult to perform conductivity measurements on single molecules. The coupling of different aromatic and heteroaromatic building blocks is difficult to achieve because substituted structures are prone to side reactions and long reaction times.
In spite of these difficulties a number of conductive molecules have been synthesized. For example, Tour et al (WO 00/01360) teaches the assembly of molecular structures consisting of phenylene/ethynylene units and the measurement of the resistance/conductivity of a self-assembled monolayer deposited on a pattern of electrodes. Molecular structures consisting of phenylene/ethynylene units have been already suggested in the literature to function as molecular wires or switches (S. J. Tour, Acc. Chem Res., 2000, 33, 791). Very few of these structures have been demonstrated to display distinct negative differential resistance (NDR) (increased resistance with increasing driving voltage) and then only under specific conditions, mostly at low temperatures.
Additionally, several groups (J. Chen et al, Science, 1999, 286, 1550; E. W. Wong et al, J. Am. Chem. Soc., 2000, 122, 5821-5840) have synthesized conducting molecules and measured the negative differential resistance behavior and conductivity of a monolayer of this material between two surfaces. C. P. Collier et al, (Science, 1999, 285, 391) have synthesized rotaxane and catenane molecules, made monolayers of these molecules using Langmuir-Blogett techniques, and demonstrated resonant tunneling current flow derived from the reversible inter-conversion between two different electronic states.
Commonly owned US-2004/0138467 discloses aromatic and aromatic/heteroaromatic molecular structures with controllable electron conducting properties which are derived from the incorporation of electron active substituents in selective positions.
The above listed references teach the synthesis of useful compounds, however they do not address the need for functionalized molecules specifically adapted for facile nano-device fabrication.